/// <summary>
/// Align our bird within the flock.
/// For every nearby bird in the system, calculate the average velocity
/// and move us towards that - this keeps us moving with the flock.
/// </summary>
/// <param name='birds'>
/// Birds. all the birds in the scene - we only really care about those in the neighbourdist
/// </param>
Vector3 Align (List<Bird> birds)
{
Vector3 steer = new Vector3 (0, 0, 0);
int count = 0;
foreach (Bird other in birds) {
float d = Vector3.Distance (m_loc, other.Location);
if ((d > 0) && (d < m_model.NeighbourDistance)) {
steer += other.Velocity;
count++;
}
}
if (count > 0) {
steer /= (float)count;
}
// As long as the vector is greater than 0
if (steer.Length () > 0) {
// Implement Reynolds: Steering = Desired - Velocity
steer.Normalize ();
steer *= m_model.MaxSpeed;
steer -= m_vel;
//steer.limit(maxforce);
steer = BirdsUtil.Limit (steer, m_model.MaxForce);
}
return steer;
}
/// A method that calculates a steering vector towards a target
/// Takes a second argument, if true, it slows down as it approaches the target
Vector3 Steer (Vector3 target, bool slowdown)
{
Vector3 steer; // The steering vector
Vector3 desired = Vector3.Subtract(target, m_loc); // A vector pointing from the location to the target
float d = desired.Length (); // Distance from the target is the magnitude of the vector
// If the distance is greater than 0, calc steering (otherwise return zero vector)
if (d > 0) {
// Normalize desired
desired.Normalize ();
// Two options for desired vector magnitude (1 -- based on distance, 2 -- maxspeed)
if ((slowdown) && (d < 100.0f)) {
desired *= (m_model.MaxSpeed * (d / 100.0f)); // This damping is somewhat arbitrary
} else {
desired *= m_model.MaxSpeed;
}
// Steering = Desired minus Velocity
//steer = target.sub(desired,m_vel);
steer = Vector3.Subtract (desired, m_vel);
//steer.limit(maxforce); // Limit to maximum steering force
steer = BirdsUtil.Limit (steer, m_model.MaxForce);
} else {
steer = Vector3.Zero;
}
return steer;
}
/// <summary>
/// Separate ourselves from the specified birds.
/// keeps us a respectable distance from our closest neighbours whilst still
/// being part of our local flock
/// </summary>
/// <param name='birds'>
/// Birds. all the birds in the scene
/// </param>
Vector3 Separate (List<Bird> birds)
{
Vector3 steer = new Vector3 (0, 0, 0);
int count = 0;
// For every bird in the system, check if it's too close
foreach (Bird other in birds) {
float d = Vector3.Distance (m_loc, other.Location);
// If the distance is greater than 0 and less than an arbitrary amount (0 when you are yourself)
if ((d > 0) && (d < m_model.DesiredSeparation)) {
// Calculate vector pointing away from neighbor
Vector3 diff = Vector3.Subtract (m_loc, other.Location);
diff.Normalize ();
diff = Vector3.Divide (diff, d);
steer = Vector3.Add (steer, diff);
count++; // Keep track of how many
}
}
// Average -- divide by how many
if (count > 0) {
steer /= (float)count;
}
// As long as the vector is greater than 0
if (steer.Length () > 0) {
// Implement Reynolds: Steering = Desired - Velocity
steer.Normalize ();
steer *= m_model.MaxSpeed;
steer -= m_vel;
//steer.limit(maxforce);
steer = BirdsUtil.Limit (steer, m_model.MaxForce);
}
return steer;
}
/// <summary>
/// Method to update our location within the scene.
/// update our location in the world based on our
/// current location, velocity and acceleration
/// taking into account our max speed
///
/// </summary>
void UpdatePositionInScene ()
{
// Update velocity
//vel.add(acc);
m_vel += m_acc;
// Limit speed
//m_vel.limit(maxspeed);
m_vel = BirdsUtil.Limit (m_vel, m_model.MaxSpeed);
m_loc += m_vel;
// Reset accelertion to 0 each cycle
m_acc *= 0.0f;
}
